menuclick-788215: Fix menu activation for <RETURN>
menuclick-788215: Fix menu activation for <RETURN>

The same 2 problems with menu click (i.e. using innerHTML and not adding
a space prefix) need solving for keyboard activation too.

Signed-off-by: Joe Walker <7a17872fbb32c7d760c9a16ee3076daead11efcf@mozilla.com>

joewalker/gcli,mozilla/gcli,joewalker/gcli,mozilla/gcli,mozilla/gcli